From ac877c64c87aff5d228cf53e40d8f68899afa815 Mon Sep 17 00:00:00 2001 From: Boris Brezillon Date: Tue, 3 Dec 2019 15:15:10 +0100 Subject: [PATCH] drm/bridge: Add the drm_bridge_get_prev_bridge() helper The drm_bridge_get_prev_bridge() helper will be useful for bridge drivers that want to do bus format negotiation with their neighbours. Signed-off-by: Boris Brezillon Reviewed-by: Laurent Pinchart Reviewed-by: Neil Armstrong Link: https://patchwork.freedesktop.org/patch/msgid/20191203141515.3597631-7-boris.brezillon@collabora.com --- include/drm/drm_bridge.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 1eb854025a209..bfb0385163f1b 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -426,6 +426,22 @@ drm_bridge_get_next_bridge(struct drm_bridge *bridge) return list_next_entry(bridge, chain_node); } +/** + * drm_bridge_get_prev_bridge() - Get the previous bridge in the chain + * @bridge: bridge object + * + * RETURNS: + * the previous bridge in the chain, or NULL if @bridge is the first. + */ +static inline struct drm_bridge * +drm_bridge_get_prev_bridge(struct drm_bridge *bridge) +{ + if (list_is_first(&bridge->chain_node, &bridge->encoder->bridge_chain)) + return NULL; + + return list_prev_entry(bridge, chain_node); +} + /** * drm_bridge_chain_get_first_bridge() - Get the first bridge in the chain * @encoder: encoder object